Not sure if the OP will return or not (seems the most entitled people demanding their free assistance are also the most fragile and run away when mocked), but if so, I have an additional question.
When you said "i tried a new control unit" does that mean a known good one from a working truck, or a new-in-box (what brand?), or a "new-as-in-different" one from a junkyard? Was that new control unit the same part number? You can't necessarily swap between auto and manual control boxes, even though the plug fits.
And yeah, what year (01-02, 03-07 classic, etc.), model (2500/3500, Kodiac, etc.), options (automatic/digital or manual controls) will really help us help you. I'm going to guess it is one of the automatic variants from your mention of a display, but like Tom said, we shouldn't have to guess.
Asshole Out! Peace :coolspot: